Telephone system



Nov. 30, 1937. E. voN D ER` LINDEN TELEPHONE SYSTEM Filed June 50, 1936 2 Sheets-Sheet 1 wwf/v70@ By E. VON DER L/NDE/V ATTORNEY NOV- 30 1937' E. VON DER I :NDEN

TELEPHONE S YSTEM Filed June 50, 1936 2 Sheets-Sheet 2 Bmw NNN QW R..

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AHORA/5y Patented Nov. 30, 1937 UNITED STATES PATENT OFICE TELEPHONE SYSVTEM- Ernst von der Linden,

Millburn, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N.'Y., a corporationof Newr York Application June 30,

5 Claims;

'I'his invention vrelates to telephone systems and more particularly to ringdown toll lines arranged to terminate at a commonbattery subscribers switchboard position'and to function' with standardlocal cord circuits thereat for either inward circuit to such a linecauses ringing current to be.

transmitted out over .the line for a single predetermined interval of time.

A related featureY resides in means for. lighting the connected cord supervisory lamp during the interval ringing current is connectedto the line. Another feature resides in means responsive to ringing current incoming over the line While a cord circuit is connected to the line at the switchboard position to cause the cord supervisory lamp to ash for a predetermined time interval and then to be retired independent of the duration of the incoming ring. e

Other features and advantages willl be clearly understood from the following detailed descriptions and by reference to the accompanying` drawings, in which Fig. 1, and the portion 0f Fig. 2 at the left of the broken line a-a' taken tol gether represent o-ne end of a two-way ringdown toll line circuit adapted to be connected to by the common batteryV cord circuit ofk a local manualswitchboard, shown at the right of the line aL-a' in Fig. 2.

Considering the combined circuit arrangement shown in Figs. l and 2 let it be assumed that a toll operator in a distant ring-down oce wishes to complete a toll call to a subscriber indicated at 22| in 2, overthe two-way ringdown toll line, one end of'Y which is shown in Figs. l and2.

The toll operator in the distant olce (not shown) rings on kthe toll line in the usual way. At the incoming end of the circuit (Fig. 1) this ringing current (20 cycles) is translated into `direct current for controlling the associated toll'line equipment and to light the line and busy lamps in front of the operator (Fig. 2). After the call has been established to the subscriber 22|the originating toll operator may transmit a ring-off y or re-ring signal by again ringing on the toll line. In this case thatY portion of Fig. 1 to the left of the vertical broken line .0r-y serves to translate the alternating current signal into one of direct current and cause the operators cord supervisory 1 lamp to ash forca denite interval of time. de-

1936, sensing. 88.134, (c1. 17o-4 1) pending on the time itV takes the rotary switch of Fig.' lto stepv to the'last terminal in the 'bank` under/the control of a timing interrupter |2|.v As the tollflne is designed fortwoway connec-y tions, a call will also be described as originating with the subscriber, 22 answered by the operators cord circuit of Fig. 2, and extended to a distant ringdown toll operation (not sho-wn) over the toll'line of Figs. land 2. On ar'connection of this kind the circuit and apparatus, Vshown to theleft of the .Verticalbroken line :c-y in Fig. 1,1 Vserves. to automatically send out 20 cycle'ringing' current over the toll line to the*v distanttoll ofce foraV deniteinterval ,ofV time. `The time interval in this Ycase being determined by the rotary switch shown in Fig.7 1, as will Vpresently bedescrib'ed.

VIncoming'.toll call When' the distant operator rings on the line,4 20 cycle ringing A'current will pass throughY the repeating coil |00, and operate relay |05,in a circuit' traced from the bottom right terminal of repeatin-g coil |00, bottom armatureand contact of re` lay |02, conductors |01, and I2?, outer bottom contact and armature of relay'20l ,conductor 224', resistance Ill, conductorfl06, outer top contact. and armature of relay |02, upper windingof re-,v peating coil |00, through Winding of relay |05., condens'enlll, and lower windingoi repeating coil |00. Relay |05operates and removes ground that normally holds slow relaserelay |04 op? erated. Relay YI0!! in releasing connects battery toilea'd |08 thereby VoperatingV relay |14., in' an. Y

|04 is Yslow to release. p

Relay H4 at its outer ibottomcont'act connects batteryto Ylead |29, to light line busy lamp`203 and to light line lamp 205 through the'bottom inner armature. and back contact of relay 20,1, thus informing theoperator of an incoming call. Relay I| 4 at its top contact connects ground to winding of relay ||0 Whichrelay operates and prepares a circuit for thelater operation ofrelay ||2. Relay H0 at its inne-r bottom contact, Y

maintains the termination resistance ||I across the talking conductors |06 and |01, and disconnects these conductors from conductors 225 and 226 respectively. Relay ||4 at contact |30 connects ground to lead I3| for operating relay 202 through its lower winding to battery. The latter relay opens, at its outer top contact, the operating circuit of relay I I3 so that this relay Will not operate and start an outgoing ringing signal when the call is answered by the operator.

Answering incoming toll call The operator, noting the lighting of lamp 205, answers the call by inserting plug 206 in jack 204 of the toll line, thereby closing a sleeve circuit through relay 200, traced from batterythroughA lamp 201, armature and back contact of relay` 209, plug sleeve 23|, thence over the.jack sleeve and through the lower and upper windings of relay 200 in series to ground. When the'plugis' seated all .the way in the vjack, battery and ground from the cord circuit repeating ,coil 2|0 is fedA back 'over the ,tip and ring conductors kofthe cord Y and toll line, uppermake contacts of relay IIO and through winding ofk relay-|12. This circuit includes thecord supervisory relay 20'9jwhich however doesnot'l operate in the above circuit due tothe highresistance of relay |.|2but,the latter relaydoes operate and closes a path for operating relay 26| from ground on lead 221 placed there i lead 228 to groundat Contact of relay 200, thus by relay 20G, and furtherltraoed over` leads |32 and |33, top armature and breakcontact of oiTf normal springs`o|26 andA lead' |34' to battery through windingof relay'il,Y The latterrelay. operates and atv its innerbottom break contact opensthe circuit'to line lampv 205 but at its inner bottoni make Vcontact continues to maintain battery on busy lamp203.:- Relay.20| at its inner top contact closes a locking circuitior itself` over eliminating relayk I|2 from itsA 'holding path. Relay120| at its outerltop break contact removes ground rom lead I 28, I thereby permitting relayv I|4 to release. Relay 20| .at its outer top makev Contact supplies .ground kfor holding relay 202 operated through its" inner top Contact and upper winding to battery, afterrelay ||4 has released.

The release of* relay II4, removes ground from lead 3Ithat previously was used to operaterelay` 2 02, opensthe ground circuit that hasbeen holding relay operatedwhich thereupon re` leases, and at contact ||5 opens the operating path of. relay 23. Relay `I I0 released, removes the termination I II from across the talkingcircuit, opens .the circuit .throughirelay V`|12, and connects conductors I|l 6 and |01 through to *conductors 225 and 226 respectively for talking. The operator, in the meantime having thrown keyZ I3 to connectvher telephone circuit 2|5, challenges the calling operator to learn the number of the wantedsubscribers station.. A

The cord supervisory lamp 201 under the above conditions remains dark d ue tov` theseries resistance of the two windings of relay `200. Uponv learning that subscriber 22| is wanted the operas peatingcoi12I0. The cord supervisory lamp 222,

controlled by relay 2|I, remains dark as long as the called subscribers receiver is oi the hook in accordance with usual practice.

Recall During the connection the distant toll operator may recall the operator in the manual ofce by ringing on the toll line in the usual manner. This ringingV signal results inY causing'the' operators cord lamp 201 to flash for a denite 'period oi time and then restores the circuits to their former condition. The manner in which this is accomplished will now be described.

The incoming ringing signal operates relay |05, causing'slow relay |04 to release and connect battery'to'lead '|08thereby operating relay ||4 Vas previously described for an incoming call.

. YThe latter relay I4 operates and at its outer top Contact connects ground to relay ||0 causing it `to operate and open the talking circuit, with the termination I I I connected across the talking conductors towards the distant toll cnice, and relay v I|2 connected across the talking conductors towards the cord 'circuit (Fig. 2).v Relay ||4 .at its'Vr inner bottom contact closes'a locking circuit to` lead |08 for holding itself operated when relay` I I3 operatesRelay I4 at contact I I5 closes the circuit for operating relay |23, traced f rornfbat-V tery through resistance |24, winding relay |23j` contact ||5 of relay I4v and lead |35to groundT at outer `top .contact of operated relayV 20|;

The operation'of relay |23j starts the operators cord llamp`2il1 nashing'in the following`manner At its outer top Contactl relay |23 closes ajcircuit for operating relay ||3 traced from batteryv through winding`v relay "l I3, lead' |36;Y top "armature and iro-nt Contact oi'operatedrelay 202, lead 236, cuter top contact of relay: |23, leads 230, 229 and 2 28, to ground at contact of' relay 2i|0. The operation of relay` II3,` at its 'inner bottom contact providesalockingpath togroundf for relay |23. -Atitsinner top contact, relay I |3y closes a battery circuit A through` the `winding of interrupter relay |22 to ground` throughinterjj rupter 2|, and at its outer bottom contacta circuit `is closed to rotary magnet |20 of a rotary timing switch `so that this switch will be made to take one step everytime relay k|22 Voperates and releases. Upon'the rst closure of ground atin-f terrupteril relay |22 operates and at its bot l tom contact connects ground Yover lead`` |31 to" the mid-point of thewin'dings of relay'200. Cord lamp201 now lights over the sleeve circuit`pre-"- viously traced, due to ground on lead |31 shuntf ing out thehigh resistance upper windingcfI relay 200. Relayl22at the same time connects groundat'its upper contacts V to rotary switch magnet |26 through the inner bottom contact off relay 3, therebycausing'switch arms I I1 and ||9 to move to Vthe first terminal in terminaly banks I|6 and ||8 respectively.' Interrupter I 2|- may providefor j any desired time interval of operating 'and releasing relay; |22 but usuallyit`- operates at I 20 interruptionspe'r minuta `When, on the rst opening of the interrupter, ground is removed from `the winding of relay |22, this' relay'releases toextinguish cord lamp 201 and to release rotary'switch magnet `I20. On the next closure of ground to relay |22, this relay reoperates to againlight the cord lamp andto` cause the rotary switch totake another step; Thus the c ord lamp 201 continues to flash until arrn ||1 o f thek switch reaches the last'terminal of switch bank IIS and connects ground tov lead |38 l a a "During this time interval, it is assumed the incfirniig ringing Vsignalffhas ceased, Ythereby re-I sulting in the' release ofrelay .I I4 'and in turn the releasev of relay |I`0. The-.latter relay I|0 as previously* described removes lthe termination mal.

|I I `from the toll line and reoonnects thelltalkingcircuit through to the operator. The operators cord lamp 201 continues to flash, however. because relay |23 ,is held operatedv by relay ||3. When 'the rotary `switch arm II1 reaches the las't'ftermi'nal, ground placed :on lead |38shunts relay.|`23, .throughthe common resistance |24 toi battery causing its release. vvThe releaseof relay |23 at its outer top contactk opens the op.' erating path for relay v||3 causing it to.release and open the circuit of interrupter relay |22. Relay |23 atits inner bottom contact alsoopens the ground path to the winding of relay 200 thereby stoppingthe flashing of cord'lamp. 201. In vthis manner the operator-is. advised ,ofA a recall-by 'the distant toll operator. If she fails toobserve the flashing signal the calling toll operator will repeat the signall and cause lamp20 to nash, for a second period.' y

j DisconnectA thesame manner as arecall signal and, assuming both -lampsare lighted, whereuponl the operator removes plugs 206 and 2|8, thus opening the-sleeve'circuit that has been holding relay 200 operated. Relay 200 releasing removes ground from the holding lead 228 to relay 20| which thereupon releases. Relay 20| releasing removes the holding ground for relay 202 which also releases, thus restoring the circuit to nor- Outgoz'ng call The operation of the toll line circuit will now be described under the assumption that the operator in the manual oiice receives a call from subscriber 22| for a connection to a distant toll point. In this case after inserting plug 2|8 in jack 2|9 and receiving the wanted subscribers number from subscriber 22|, the operator inserts plug 205 in toll line jack 294 in order to reach the distant toll cnice. 'Ihe toll line circuit is so arranged that when plug 206 is inserted in jack 204, a ringing signal is automatically caused to be sent out over the line to the distant toll office. This is accomplished as the result of operating relay 200 on the plug-in which connects ground to lead 228. 'I'his ground path is traced over lead 229, inner bottom normal contact of relay 202, leads 231 and |39 to battery through Winding of relay ||0. The latter relay operates to split the talking circuit as previously described and to connect relay H2 across the talking conductors 225 and 226. Relay ||2 then operates on battery received from the cord circuit and closes a contact for operating relay 20|, over a path traced from battery through Winding of relay 20| lead |34, contact and armature on off-normal springs |26, leads |33 and |32, contact of relay ||2 to ground placed on lead 221 by relay 200. The operation of relay er bottom;,'contactsmf-relay 202. Relay |02A Y thereupon operates to connect v'20fcycle' continuous i-ing'ingfcurrent` through ballast'lampzlfl. Y

to the windings'of repeating .coil^i|0i| and thence over the linezto` 'the 'distant :toll ice; .'gRelay |02; at its inner .top .contact lalso closes '.a'shunt around relay' I05 :t'o prevent its'operation zon the ringing ,current. I 1 The o ringing signal; con-`v tinues until stopped by the action of thejrotary switch shown in.,Fig.Y 1 which will ynow be defscrlbed. .z x "f l: *l

When relay 3 first operatedyit connected battery at its innertop contactatdthe Winding of relay.;|22 thereby causing this; relay 5toi ,operate and release under control of linterrupter |2|. Relay ||3 at its outer bottomcontact also closed a circuit 13o-rotary switch mag-net Y.|20 which includes a contact; ofgrelayY |22 thereby causing the rotary switch to step under control of interrupter |2|. ,'At V,this point rit yshould be observed rthatthe operators cordsupervisory lamp 201 remains lighted during theperiod that the rineinasienal Sfbe/ne VSent out. duf-nio ground, at4 theujnner` bottom contactuofVv relay I I3, being connected to the middle ofV thermeings tof. relay .2.0.0. .over flearlairlV iraffds thrligh inner bottom normal contact of relay |23 and lead |31. When the switch arm ||9 reaches the fourth terminal in the-bank ||8 it connectsground to lead |4| which operates relay 202 through its. uppery winding tobattery. Relay 202, at its inner top contact locks to the outer top contact on operated relay 20|, stops the ringing signal from going out, restores the rotary switch to normal, and reconnects the toll release of relay ||3Y connects ground, at its lnner bottom contact, through contact |42 o-f off-normal springs |26 to operate the release mag,- net |25, thereby restoring the rotary'switchto normal. 'I'he toll line conductors |06 and |01 are reconnected to conductors 225 and 226 for talking due to the release of relay ||0 which is causedV by the opening of contact |43 oftheoiT-normal springs |26 when the switch restores to normal. The holding path for relay ||0 is traced over lead |39, outer bottomV contact of relay |23, contact |43 of oil-normal springs |26, leads |33 and |32, contact of relay ||2 and thence over leadY 221 to ground at contact of relay 200. All relaysk Y of the toll line circuit are .thus restored to nor-V mal except relays 200, 20| and 202 whichfare the same relays `that remain operatedron an incoming callpreviously described; The cord lamp 201 is extinguished due to release of relay `|I3 thus leaving the circuits in a condition to receive a recall signal in the manner previously described.

Disconnect Assuming conversation has terminated on the abovedescribed connection, the manual operator will proceed to disconnect as soon as she receives a disconnect lamp signal 222 indicating that the calling subscriber 22| has restored his receiver to the switchhook and Withouty waiting to receive a ilashing `ring-off signal on lamp 201 because she is the originating operator holding a ticket on the connection. Said operator therefore may or may not have received a iiashing disconnect lamp 201. If, however, the plug 206 is removed from vjack 204 before lamp 201 ashes the operator must send a ring-ofi signal vto the distant toll oice. 'I'his is accomplished by'reinserting plug 206 in the toll line jack long enough to cause a ringing signal to be sent tothe distant toll o'ice, in the same manner as previously described in originating the call.

What is claimed is: '1.In a telephone system, an operators position,-a line terminating thereat, acornmon battery cordcircuit atsaid position including asupervisory signal device adapted to be connected to said line, a source of ringing current, and means in said line responsive to the connection of said cord with the line for connecting said source .to the line and displaying said supervisory signal for a predetermined time interval.

2. In a telephone system, an operators position, a line terminating thereat, a common battery cord circuit at said position including a supervisory signal device adapted to be connected to'said line, a source of ringing current, and

means including Ya selector switch in said line responsive to connection of saidcord With the line for connecting said source tothe line and displaying said supervisory signal for a predetera line terminating thereat, a common battery cord circuit at said position including av supervisory signal device connected to said line,` and means-associated With said line and'respo'nsive to ringing current incoming over said line for intermittently displaying said supervisory signal for a predetermined interval of time irrespective of the length of the incomingv ring.

5. In a telephone system, al telephone line extending vbetween a first and second exchange, a cord circuit at said second exchange including a supervisory signal device, a source of ringing current, means including a selector switch in said line responsive to the connection of said cord with said line for connecting said source to said line for a predetermined interval of time, said selec- .tor switch also being responsive to the transmission of signaling current over said line from the first exchange for displaying said cord circuit supervisory signal for a predetermined interval of time irrespective of the length of the incoming ring.

ERNST VON DER LINDEN. 

